Novel polystyrene modified sewage treatment filter material

Abstract

A preparation method of the novel polystyrene modified sewage treatment filter material comprises the following steps: S1, ozone oxidation treatment: filling pretreated expanded polystyrene foam balls into a reactor, carrying out ozone oxidation treatment on the expanded polystyrene foam balls by virtue of an ozone generator, and after the treatment is finished, cooling to room temperature; washing with clear water until the pH value of the washing liquid is constant, and drying at the constant temperature of 60-80 DEG C for 2-4 hours; s2, preparing a precursor solution: adding the ferric salt solution and the auxiliary agent solution into a reactor, and ultrasonically dispersing to be uniform, so as to obtain the precursor solution; s3, preparing a modified filter material: preparing an iron-based compound modified filter material from the foamed polystyrene foam balls treated in S1 and the precursor solution obtained in S2 by using an in-situ hydrothermal synthesis method, and performing post-treatment to obtain the core-shell type modified polystyrene filter material. The hydrophilicity and biocompatibility of the polystyrene filter material can be remarkably improved, so that the sewage treatment efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment materials, and particularly to a novel polystyrene-modified sewage treatment filter medium. Background Art

[0002] In the process of water treatment, filtration technology plays a key role, and the selection and application strategy of filter media directly affect the final treatment effect. As a light suspended filter medium, polystyrene is gradually becoming a new favorite in the field of synthetic filter media due to its wide applicability and unique filtration advantages.

[0003] Polystyrene foam filter balls have significant advantages: First, their bulk density is only 15 to 80 kg / m³, much lower than that of quartz sand (1800 to 2000 kg / m³), which gives polystyrene filter balls obvious advantages in terms of transportation, installation, and labor costs. Second, the particle size of the filter balls is uniform, which can maximize the ability of the entire filter bed to intercept dirt, thus ensuring excellent effluent quality.

[0004] However, despite the many advantages of polystyrene filter balls, some problems have also emerged in their application:

[0005] 1. Biocompatibility of the filter medium surface

[0006] As a carrier of biofilm in the filter tank, polystyrene plays a treatment role through biofilm during filtration. Although polystyrene can provide a rich attachment space for biofilm due to its large specific surface area, its natural hydrophobicity and low biocompatibility limit the rapid attachment, growth, and reproduction process of microorganisms, resulting in a longer system startup period, and in the stable operation stage, the biofilm structure on the surface of the filter medium may not be tight enough. In contrast, inorganic filter media are usually more superior in terms of biological activity and organic matter degradation efficiency.

[0007] 2. Influence of backwashing on treatment effect

[0008] The backwashing operation has a complex impact on the efficacy of the polystyrene biological filter tank. Due to the biocompatibility problem of polystyrene filter balls, once the biofilm detaches, the reattachment is not instantaneous, which will significantly weaken its pollutant treatment ability in the short term. In fact, the treatment efficiency may decline for some time after backwashing.

[0009] In view of the inherent biological incompatibility of polystyrene and the low film-forming efficiency, there are some solutions in the prior art. For example, protein molecules are fused onto the surface of polystyrene, and its surface properties are reshaped by physical means, thereby enhancing its biocompatibility, improving its biological adhesion and growth potential. The modified filter media obtained by this method shows significant advantages in the film-forming speed, and the surface biological load is increased by about two times compared with the untreated filter media. However, the physical adsorption mechanism makes the binding of protein molecules to the polystyrene surface unstable. After long-term operation, as the protein falls off or is decomposed by microorganisms, the biomass on the filter media surface will gradually decrease, thus affecting the backwashing start time and sewage treatment efficiency.

[0010] In the prior art, protein molecules are also attached to polystyrene filter balls by chemical bonding for modification. This modification significantly improves the hydrophilic performance of the filter media, significantly reduces its surface contact angle, and enhances the surface energy accordingly. After modification, the membrane-forming process of the filter media is significantly accelerated, and the biological load after membrane formation is two to three times higher than that of the untreated filter media. However, the cost of this method for protein molecules is relatively high, and in long-term operation, it may be gradually consumed due to the metabolic action of microorganisms, limiting the feasibility of this technology in large-scale applications. Summary of the Invention

[0011] The purpose of the present invention is to provide a new type of polystyrene-modified sewage treatment filter media to solve the technical problems proposed in the above background technology.

[0012] To achieve the above purpose, the present invention adopts the following technical solutions:

[0013] A new type of polystyrene-modified sewage treatment filter media, the preparation method includes the following steps:

[0014] S1 Ozone oxidation treatment: Load the pretreated expanded polystyrene foam balls into the reactor, and carry out ozone oxidation treatment on the expanded polystyrene foam balls through an ozone generator. After the treatment is completed, rinse with clean water until the pH value of the rinse liquid is constant, and dry at a constant temperature of 60 - 80 °C for 2 - 4 h;

[0015] S2 Prepare the precursor solution: Add the iron salt solution and the auxiliary solution into the reactor, and ultrasonically disperse until homogeneous to obtain the precursor solution;

[0016] S3 Preparation of modified filter media: Use the in-situ hydrothermal synthesis method to prepare iron-based composite modified filter media from the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2, and obtain core-shell modified polystyrene filter media after post-treatment.

[0017] Further, in step S1, the pre-treatment method is as follows: Screen expanded polystyrene foam balls with a particle size of 3-5 mm and a bulk volume of 40 L, wash and dry them, soak them in water for 24-30 h, then rinse them with water until the pH value of the rinse liquid remains constant, and then dry them at a constant temperature of 60-80 °C for 1-6 h.

[0018] Further, in step S2, the iron salt includes soluble iron salts; the auxiliary agent includes soluble sulfates.

[0019] Further, the iron salt includes one of ferric nitrate anhydrous, ferric sulfate anhydrous, and ferric chloride anhydrous.

[0020] Further, the auxiliary agent is anhydrous sodium sulfate.

[0021] Further, the concentration of the iron salt solution is 0.01-0.1 mol / L, and the concentration of the auxiliary agent solution is 0.01-0.1 mol / L.

[0022] Further, in step S3, the method for preparing the iron-based composite modified filter material by the in-situ hydrothermal synthesis method is as follows: Under stirring conditions, the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2 are subjected to a water bath heating reaction at a volume ratio of 1-5:3-15.

[0023] Further, the rotation speed of the stirring conditions is 150-250 rpm.

[0024] Further, the temperature of the water bath heating is 40-100 °C, and the reaction time is 1-12 h.

[0025] Further, the post-treatment method is that the iron-based composite modified filter material is rinsed with water until the rinse liquid has no color and the pH value remains constant, and then dried at 60-80 °C for 1-3 h.

[0026] The principles of each step in the preparation method of the present invention are as follows:

[0027] S1: Ozone decomposes to generate reactive oxygen free radicals with extremely strong oxidizing and non-selective oxidizing properties, oxidize the carbon-carbon double bonds on the surface of polystyrene, partially oxidize the hydrophobic benzene ring structure, generate oxygen-containing polar hydrophilic groups, and form hydrophilic surface micro-regions, thereby improving the hydrophilicity of polystyrene; this step can significantly improve the hydrophilicity of polystyrene, but its biocompatibility is still insufficient.

[0028] S2: Configure iron salts and auxiliary agents into a precursor solution that provides an iron oxide coating, facilitating the subsequent introduction of iron oxides onto the surface of polystyrene; the iron salt serves as an iron source, hydrolyzes to generate iron oxides, and the auxiliary agent is used to adjust the ionic strength, prevent premature precipitation of the iron salt, enhance the solution stability, inhibit aggregation, and ensure uniform nucleation and deposition of iron oxides.

[0029] S3: Accelerate the hydrolysis of iron salt by water bath heating to promote the in-situ generation of iron oxides, and make the iron oxides adhere to the surface of polystyrene after ozone treatment to form a core-shell structure. The high specific surface area of iron oxides can increase the microbial attachment sites, promote biofilm formation, improve biocompatibility, and at the same time increase the biointerception area. Moreover, the iron oxides themselves contain hydrophilic groups, which can reduce the surface affinity energy of polystyrene filter media and further increase the surface hydrophilicity of polystyrene filter media.

[0030] The beneficial effects of the present invention compared with the prior art are as follows:

[0031] In the present invention, the surface of polystyrene is oxidized by ozone to oxidize the carbon-carbon double bonds on the surface of polystyrene, significantly improving the hydrophilic performance of polystyrene. By introducing iron oxides on the surface of polystyrene, the biocompatibility of polystyrene is improved, the biointerception area of the filter balls is increased, and the microbial interception ability is improved. Moreover, the hydrophilic oxide layer is evenly distributed and not easy to fall off, will not cause secondary pollution, has stable and long-lasting hydrophilicity and biocompatibility, effectively improves the film-forming speed and film-forming amount on the surface of polystyrene filter media, thereby improving the removal rate of pollutants. At the same time, by improving the biocompatibility of polystyrene filter media, during the backwashing process, the backwashing time and water volume can be greatly reduced, the backwashing energy consumption can be reduced, and the operation cost can be effectively reduced. Description of the Drawings

[0032] Figure 1 is the static contact angle test result of Example 1 of the present invention;

[0033] Figure 2 is the static contact angle test result of Comparative Example 1 of the present invention. Detailed Embodiments

[0034] To make the objectives, technical solutions and advantages of the present invention clearer, the following lists preferred embodiments with reference to the accompanying drawings and further elaborates on the present invention. However, it should be noted that many details listed in the specification are only for readers to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0035] A new type of polystyrene modified sewage treatment filter media, the preparation method includes the following steps:

[0036] S1 Ozone oxidation treatment: Load the pre-treated expanded polystyrene foam balls into the reactor in proportion, and carry out ozone oxidation treatment on the expanded polystyrene foam balls through an ozone generator. After the treatment is completed, rinse with clean water until the pH value of the rinse liquid is constant, and dry at 60°C for 2h;

[0037] The method of the pretreatment is as follows: Screen expanded polystyrene foam balls with a particle size of 3 - 5 mm and a bulk volume of 40 L, wash and dry them, soak them in water for 24 h, then rinse them with water until the pH value of the rinse liquid remains constant, and after rinsing, dry them at a constant temperature of 60 °C for 4 h;

[0038] S2 Prepare the precursor solution: Add an iron salt solution with a concentration of 0.01 - 0.1 mol / L and an auxiliary agent solution with a concentration of 0.01 - 0.1 mol / L into the reactor, and ultrasonically disperse them until they are homogeneous to obtain the precursor solution;

[0039] S3 Prepare the modified filter material: Use the in-situ hydrothermal synthesis method to prepare an iron-based composite modified filter material from the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2, and obtain a core-shell modified polystyrene filter material after post-treatment; the core-shell modified polystyrene filter material includes a spherical core body and a shell body; the spherical core body is a regular spherical polystyrene sphere; the shell body is iron oxide arrayed on the surface of the spherical core body.

[0040] The method for preparing the iron-based composite modified filter material by the in-situ hydrothermal synthesis method is as follows: Under the stirring condition with a rotation speed of 150 - 250 rpm, mix the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2 at a volume ratio of 1 - 5:3 - 15, and carry out a water bath heating reaction at a temperature of 40 °C - 100 °C for 1 - 12 h.

[0041] The method of the post-treatment is as follows: After rinsing the iron-based composite modified filter material with water until the rinse liquid has no color and the pH value remains constant, dry it at 60 °C for 1 h.

[0042] In step S2, the iron salt includes soluble iron salts; the auxiliary agent includes soluble sulfates.

[0043] The iron salt includes one of ferric nitrate anhydrous, ferric sulfate anhydrous, and ferric chloride anhydrous.

[0044] The auxiliary agent is anhydrous sodium sulfate.

[0045] The following is illustrated by more specific examples:

[0046] Example 1

[0047] A new type of polystyrene modified sewage treatment filter material, the preparation method includes the following steps:

[0048] S1 Ozone oxidation treatment: Screen expanded polystyrene foam balls with a particle size of 3 - 5 mm and a bulk volume of 40 L, wash and dry them, soak them in water for 24 h, then rinse them with water until the pH value of the rinse liquid remains constant. After rinsing, dry them at a constant temperature of 60 °C for 4 h; After drying, load the expanded polystyrene foam balls into the reactor in proportion, and carry out ozone oxidation treatment on the expanded polystyrene foam balls through an ozone generator. After the treatment, rinse them with water until the pH value of the rinse liquid is constant, and dry them at a constant temperature of 60 °C for 2 h;

[0049] S2 Preparation of precursor solution: Add 0.1 mol / L ferric chloride solution and 0.1 mol / L anhydrous sodium sulfate solution into the reactor, and ultrasonically disperse them until homogeneous to obtain the precursor solution;

[0050] S3 Preparation of modified filter material: Under the stirring condition with a rotation speed of 150 rpm, react the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2 at a volume ratio of 1:3 in a water bath at a temperature of 60 °C for 10 h to obtain an iron-based composite modified filter material. Then rinse the iron-based composite modified filter material with water until the rinse liquid has no color and the pH value remains constant, and then dry it at 60 °C for 1 h to obtain a core-shell type modified polystyrene filter material.

[0051] Example 2

[0052] A new type of polystyrene modified sewage treatment filter material, the preparation method includes the following steps:

[0053] S1 Ozone oxidation treatment: Screen expanded polystyrene foam balls with a particle size of 3 - 5 mm and a bulk volume of 40 L, wash and dry them, soak them in water for 24 h, then rinse them with water until the pH value of the rinse liquid remains constant. After rinsing, dry them at a constant temperature of 60 °C for 4 h; After drying, load the expanded polystyrene foam balls into the reactor in proportion, and carry out ozone oxidation treatment on the expanded polystyrene foam balls through an ozone generator. After the treatment, rinse them with water until the pH value of the rinse liquid is constant, and dry them at a constant temperature of 60 °C for 2 h;

[0054] S2 Preparation of precursor solution: Add 0.01 mol / L ferric chloride solution and 0.01 mol / L anhydrous sodium sulfate solution into the reactor, and ultrasonically disperse them until homogeneous to obtain the precursor solution;

[0055] S3 Preparation of modified filter material: Under the stirring condition with a rotation speed of 150 rpm, react the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2 at a volume ratio of 1:3 in a water bath at a temperature of 60 °C for 10 h to obtain an iron-based composite modified filter material. Then rinse the iron-based composite modified filter material with water until the rinse liquid has no color and the pH value remains constant, and then dry it at 60 °C for 1 h to obtain a core-shell type modified polystyrene filter material.

[0056] Example 3

[0057] A new type of polystyrene-modified sewage treatment filter material, and the preparation method includes the following steps:

[0058] S1 Ozone oxidation treatment: Screen expanded polystyrene foam balls with a particle size of 3-5 mm and a bulk volume of 40 L, wash and dry them, soak them in clean water for 30 h, then rinse with clean water until the pH value of the rinse liquid remains constant. After rinsing, keep them at a constant temperature of 70 °C and dry for 6 h; After drying, load the expanded polystyrene foam balls into the reactor in proportion, and carry out ozone oxidation treatment on the expanded polystyrene foam balls through an ozone generator. After the treatment, rinse with clean water until the pH value of the rinse liquid remains constant, and keep them at a constant temperature of 80 °C and dry for 3 h;

[0059] S2 Prepare the precursor solution: Add a 0.01 mol / L ferric nitrate solution and a 0.01 mol / L anhydrous sodium sulfate solution into the reactor, and ultrasonically disperse them until they are homogeneous to obtain the precursor solution;

[0060] S3 Prepare the modified filter material: Under the stirring condition with a rotation speed of 200 rpm, react the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2 at a volume ratio of 3:8 in a water bath at a temperature of 100 °C for 8 h to obtain an iron-based composite modified filter material. Then, rinse the iron-based composite modified filter material with clean water until the rinse liquid has no color and the pH value remains constant, and then dry it at 70 °C for 3 h to obtain a core-shell type modified polystyrene filter material.

[0061] Example 4

[0062] A new type of polystyrene-modified sewage treatment filter material, and the preparation method includes the following steps:

[0063] S1 Ozone oxidation treatment: Screen expanded polystyrene foam balls with a particle size of 3-5 mm and a bulk volume of 40 L, wash and dry them, soak them in clean water for 28 h, then rinse with clean water until the pH value of the rinse liquid remains constant. After rinsing, keep them at a constant temperature of 80 °C and dry for 1 h; After drying, load the expanded polystyrene foam balls into the reactor in proportion, and carry out ozone oxidation treatment on the expanded polystyrene foam balls through an ozone generator. After the treatment, rinse with clean water until the pH value of the rinse liquid remains constant, and keep them at a constant temperature of 70 °C and dry for 4 h;

[0064] S2 Prepare the precursor solution: Add a 0.05 mol / L ferric sulfate solution and a 0.05 mol / L anhydrous sodium sulfate solution into the reactor, and ultrasonically disperse them until they are homogeneous to obtain the precursor solution;

[0065] Preparation of S3 modified filter media: Under the stirring condition with a rotation speed of 250 rpm, the foamed polystyrene foam balls after S1 treatment and the precursor solution obtained from S2 were heated and reacted in a water bath at 40 °C for 12 h at a volume ratio of 5:15 to obtain iron-based composite modified filter media. Then, the iron-based composite modified filter media were rinsed with clear water until the rinsing liquid had no color and the pH value remained constant, and then dried at 80 °C for 2 h to obtain core-shell modified polystyrene filter media.

[0066] Comparative Example 1

[0067] A new type of polystyrene modified sewage treatment filter media, and the preparation method includes the following steps:

[0068] S1 ozone oxidation treatment: Screen foamed polystyrene foam balls with a particle size of 3 - 5 mm and a bulk volume of 40 L, wash and dry them, soak them in clear water for 24 h, then rinse them with clear water until the pH value of the rinsing liquid remains constant, and after rinsing, dry them at a constant temperature of 60 °C for 4 h; After drying, load the foamed polystyrene foam balls into the reactor in proportion, and carry out ozone oxidation treatment on the foamed polystyrene foam balls through an ozone generator. After the treatment, rinse them with clear water until the pH value of the rinsing liquid is constant, and dry them at a constant temperature of 60 °C for 2 h to prepare the filter media.

[0069] 1. Static contact angle test of filter media.

[0070] The filter media prepared in Example 1 and Comparative Example 1 were used to conduct a static contact angle test on water at 20 °C by the sessile drop method, as Figure 1-2 shown.

[0071] As can be seen from Figure 1-2 , the static contact angle of Example 1 was 62.2°, while the static contact angle of Comparative Example 1 was 96.6°, which was much larger than that of Example 1, indicating that this application can significantly improve the hydrophilic performance of polystyrene filter media.

[0072] 2. Sewage treatment experiment

[0073] The process equipment for this test was mainly an aerated biological filter. The pool body was cylindrical, using an organic glass column with a diameter of 200 mm and a column height of 1500 mm.

[0074] The filter media prepared in Examples 1 - 2 and Comparative Example 1 were paved in the biological filter for a static biofilm formation experiment. The inoculated activated sludge and sewage were mixed and then pumped into the reactor by a pump, and then left to stand for 6 - 8 hours to allow the sludge to contact the carrier to play the role of inoculating microorganisms. After that, all were discharged, and then sewage without sludge was continuously fed, and the water inflow was gradually increased until the biofilm formation was completed.

[0075] The sludge was taken from the return sludge of the aerobic aeration tank of a sewage treatment plant in Nanning. After the filter media was soaked with the inoculated sludge for 8 hours, the sludge was drained, and then the prepared sewage was introduced, which was replaced every 12 hours. The water temperature was about 20°C.

[0076] After the biofilm formation startup was completed and a biofilm appeared on the surface of the filter media, the removal effect of pollutants was tested by sampling after stable operation.

[0077] After testing, the nitrate nitrogen content in the effluent of the filter tank in Example 1 was 3 mg / L, and the removal rate of nitrate nitrogen was 90%; the nitrate nitrogen content in the effluent of the filter tank in Example 2 was 3.6 mg / L, and the removal rate of nitrate nitrogen was 88%; the nitrate nitrogen content in the effluent of the filter tank in Comparative Example 1 was 12 mg / L, and the removal rate of nitrate nitrogen was 60%.

[0078] Thus, it can be seen that this application can significantly improve the removal effect of sewage pollutants by improving the hydrophilicity and biocompatibility of polystyrene.

[0079] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A new type of polystyrene-modified sewage treatment filter material, characterized in that, The preparation method comprises the following steps: S1 Ozone oxidation treatment: Fill the pretreated expanded polystyrene foam balls into a reactor, and conduct ozone oxidation treatment on the expanded polystyrene foam balls through an ozone generator. After the treatment, rinse with clear water until the pH value of the rinse liquid is constant, and dry at a constant temperature of 60 - 80 °C for 2 - 4 h; S2 Preparation of precursor solution: Add an iron salt solution and an auxiliary agent solution into the reactor, and ultrasonically disperse until uniform to obtain a precursor solution; S3 Preparation of modified filter material: Use the in-situ hydrothermal synthesis method to prepare an iron-based composite modified filter material from the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2, and obtain a core-shell modified polystyrene filter material after post-treatment.

2. The novel polystyrene-modified sewage treatment filter material according to claim 1, wherein: In step S1, the method of the pretreatment is: Screen expanded polystyrene foam balls with a particle size of 3 - 5 mm and a bulk volume of 40 L, wash and dry them, soak them in clear water for 24 - 30 h, then rinse with clear water until the pH value of the rinse liquid remains constant, and dry at a constant temperature of 60 - 80 °C for 1 - 6 h after rinsing.

3. A novel polystyrene-modified sewage treatment filter medium according to claim 1, characterized in that: In step S2, the iron salt includes a soluble iron salt; the auxiliary agent includes a soluble sulfate.

4. A novel polystyrene-modified sewage treatment filter material according to claim 3, characterized in that: The iron salt includes one of ferric nitrate anhydrous, ferric sulfate anhydrous, and ferric chloride anhydrous.

5. A novel polystyrene-modified sewage treatment filter material according to claim 3, characterized in that: The auxiliary agent is anhydrous sodium sulfate.

6. A novel polystyrene-modified sewage treatment filter medium according to claim 1, characterized in that: The concentration of the iron salt solution is 0.01 - 0.1 mol / L, and the concentration of the auxiliary agent solution is 0.01 - 0.1 mol / L.

7. A novel polystyrene-modified sewage treatment filter material according to claim 1, characterized in that: In step S3, the method for preparing the iron-based composite modified filter material by the in-situ hydrothermal synthesis method is: Under stirring conditions, mix the expanded polystyrene foam balls treated in S1 and the precursor solution obtained in S2 at a volume ratio of 1 - 5:3 - 15, and carry out a water bath heating reaction.

8. A novel polystyrene-modified sewage treatment filter medium according to claim 7, characterized in that: The rotation speed of the stirring conditions is 150 - 250 rpm.

9. A novel polystyrene-modified sewage treatment filter material according to claim 7, characterized in that: The temperature of the water bath heating is 40 - 100 °C, and the reaction time is 1 - 12 h.

10. A novel polystyrene-modified sewage treatment filter medium according to claim 1, characterized in that: The post-treatment method is that after the iron-based composite modified filter material is rinsed with clear water until the rinse liquid has no color and the pH value remains constant, it is dried at a constant temperature of 60 - 80 °C for 1 - 3 h.

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